The overall objectives are an analysis of the factors controlling the cessation of cell growth under conditions of high cell density and the resumption of growth when conditions of low cell density are restored. A sensitive parameter of cellular growth is macromolecular synthesis; in particular protein, RNA, and DNA. Emphasis is therefore placed on ascertaining those factors that may be closely related to both the onset and the decline of the synthesis of these macromolecules during the growth cycle. BIBLIOGRAPHIC REFERENCE: Cheung, C. P., and Marcus, A., Guanine Nucleotide Determination in Extracts of Wheat Embryo. FEBS Lett. 70, 141-144 (1976).